Study Pinpoints Just How Much Exercise Is Good for Mental Health

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John Allegrante

Carol Ewing Garber

Teachers College researchers help show that people who exercise 2.5 to 7.5 hours per week report better mental health—but more can be too much of a good thing

Scientists and devotees of regular exercise have long known that fitness keeps minds healthy as well as bodies. In addition to regulating weight and building physical strength, exercise improves self-esteem, mitigates anxiety, calms the nerves and elevates the mood and vitality. But what is the optimum amount of physical activity associated with better mental health?

Now, a research team led by professors at Teachers College, Columbia University has come up with an answer: 2.5 to 7.5 hours of exercise per week, depending on gender, age and general physical health. A novel finding of the study conducted by exercise, behavioral, and health education scientists revealed that exercising more than 7.5 hours per week was associated with diminished mental health.

“Apart from the considerable physical health-related benefits, a number of psychological benefits have been identified, with the most evidence about depression and anxiety,” says the report, “Relationship between Physical Activity and General Mental Health,” published online ahead of print in the September, 2012 issue of Preventive Medicine.

The scientists, led by Yeon Soo Kim, M.D., a member of the faculty of Seoul National University who was a visiting scholar in the Teachers College Departments of Biobehavioral Sciences and Health and Behavior Studies while the study was conducted, found that individuals who engaged in the optimal amount of physical activity were more likely to report better mental health than those who did not. The study was done by using self-reported data from a national random sample of 7,674 adult respondents collected during the 2008 U.S. Health Information National Trends 2007 Survey (HINTS), and analyzed in 2012. A measure of mental health was plotted against the number of hours of physical activity per week.

“The largest mental health differences occurred with two to four hours of exercise per week,” the report says. “Beyond four hours, the trend begins to reverse: about 65 percent of those with poorer mental health exercised more than four hours per week, compared to 55 percent of adults in better mental health.” In a surprising and novel finding, the team found that, after 7 ½ hours per week, symptoms of depression and anxiety increased sharply. Similar trends were observed “irrespective of gender, age or physical health status,” the report says.

This is the first study confirming that too much exercise can be related to poor mental health, said Carol Ewing Garber of Teachers College, who added that she has been interested in whether exercise can become addictive for people who rely on it as a mood elevator. But she cautioned that researchers need to do randomized controlled studies to discover exactly how exercise and mood are related. For example, are people who tend to be depressed and anxious more likely to engage in extended physical exercise as a way of keeping their mental symptoms under control? Or do repeated, long-lasting exercise sessions—sometimes termed overtraining syndrome—actually cause symptoms of depression and anxiety?

Nevertheless, the broader significance of the study is that it supports “the notion that regular activity may lead to prevention of mental health disorders,” the authors write.

“If physical activity can prevent mental health disorders or improve overall mental health, the public health impact of promoting physical activity could be enormous,” the report says, adding that “depression [and anxiety disorders are] highly debilitating [and] result in significant impairment in social and occupational functioning.”

The team of researchers includes Ewing Garber; John P. Allegrante of Teachers College and the Mailman School of Public Health, Columbia University; Yoon Soo Park of the University of Illinois at Chicago; Ray Marks of the School of Health and Behavior Sciences, York College, City University of New York; Haean Ok of the Department of Sports Industry and Science, Mokwon University, Daejeon City, Republic of Korea; and Kang Ok Cho of the Health and Exercise Science Laboratory, Institute of Sports Science, Seoul National University, Seoul, Republic of Korea.